A Study of CEA-Pre-Targeted Radioligand Therapy (CEA-PRIT 2.0) in Participants with Colorectal Cancer

1. Why is this study needed?

Colon cancer is impacting a lot of patients worldwide. While initial treatments for colon cancer might be effective, cancer cells are incredibly adaptable, and many people develop an advanced disease when the cancer spreads all over the body. For these people, there remains a high unmet medical need for more effective treatment options with better safety.

This study is testing a new treatment called CEA-PRIT 2.0 which is being developed to treat people with a certain type of colon cancer, called colorectal cancer. CEA-PRIT 2.0 consists of three individual components (two antibodies and a radioactive substance). The radioactive substance binds to an antibody to target and kill cancer cells. In addition to CEA-PRIT 2.0, some participants will also receive an imaging agent to see where the treatment goes in your body, if it reaches your cancer and to determine how much radiation will go to your organs and tumors.

CEA-PRIT 2.0 is an experimental medicine. This means health authorities (like the U.S. Food and Drug Administration and European Medicines Agency) have not approved CEA-PRIT 2.0 for the treatment of colorectal cancer.

This study aims to test how safe CEA-PRIT 2.0 is (at different doses), to understand what happens to CEA-PRIT 2.0 once it is in the body, and what CEA-PRIT 2.0 does to your body and your disease.

2. Who can take part in the study?

People aged 18 years and older with a certain type of colon cancer (called MSS CRC) can take part in this study if they have progressed after having received available therapies.

People may not be able to take part in this study if they have certain ongoing medical conditions or are pregnant or currently breastfeeding. People who are planning to become pregnant during or shortly after the trial are not able to participate.

3. How does this study work?

People will be examined to check if they are able to participate in the study. The screening period will take place from 1 to 28 days before the start of treatment. Everyone who joins this study will be given CEA-PRIT 2.0 with the two antibodies as an infusion into the vein and the radioactive substance as an injection into the vein, each on separate treatment days, with treatment cycles every few weeks.

This is an open-label study. This means everyone involved, including the participant and the study doctor, will know the study treatment the participant has been given.

During this study, the study doctor will see participants at least 2 or as many as 11 times during each treatment cycle (depending on the treatment cycle). They will see if the treatment is working and check for any unwanted effects participants may have. Participants will have follow-up visits regularly after completing the study treatment, during which the study doctor will check on the participant’s wellbeing. Total time of participation in the study will be about 6 months to one year depending on the timing of treatment administration; this is followed by a 5-year safety follow up. Participants have the right to stop study treatment and leave the study at any time, if they wish to do so.

4. What are the main results measured in this study?

The main purpose of the study is to check if the treatment with CEA-PRIT 2.0 is safe. This is done by measuring the number and seriousness of any unwanted effects that may occur after receiving the study treatment as well as after completing the treatment.

Other key results measured in the study include:

Find out where the treatment goes in your body, if it reaches your cancer and determine how much radiation will go to your organs and tumors.

Determine the appropriate treatment dose and time interval for treatment administration.

The results are assessed at various times, such as after certain doses are administered, and through medical scans and tests that measure the cancer's response to the drugs.

5. Are there any risks or benefits in taking part in this study?

Taking part in the study may or may not make participants feel better. But the information collected in the study can help other people with similar health conditions in the future.

It may not be fully known at the time of joining the study how safe and how well the study treatment works. The study involves some risks to the participant. But these risks are generally not greater than those related to routine medical care or the natural progression of health conditions. People interested in taking part will be informed about the risks and benefits, as well as any additional procedures or tests they may need to undergo. All details of the study will be described in an informed consent document. This includes information about possible effects and other options of treatment.

Risks associated with the study drugs
Participants may have unwanted effects due to the treatment used in this study. These unwanted effects can be mild to severe, even life-threatening, and vary from participant to participant. During this study, participants will have regular check-ups to see if there are any unwanted effects.

CEA-PRIT 2.0 has not yet been tested in humans. Therefore, the unwanted effects of this medicine are not known now. Participants will be told about the possible unwanted effects based on laboratory studies or knowledge of similar medicines.

These potential unwanted effects are based on what is known about radiation exposure, side effects related to the treatment targeting areas outside the tumor, and effects commonly seen with similar types of treatments.

Possible unwanted effects may include:

• Reactions during and after infusion (infusion-related reactions/cytokine release syndrome)
• Leakage from the injection site
• Development of antibodies against CEA-PRIT 2.0
• Side effects involving the stomach, intestine, kidney, bladder, and liver.
• Side effects on blood cells, such as low blood cell counts caused by radiation
• Side effects caused by long-term exposure to radiation
• Inability to produce children

The administered study treatment may be harmful to an unborn baby. Women and men must take precautions to avoid exposing an unborn baby to the study treatment.